var Set = {
  
  count: function(set) {
    
    var n;
    var result = 0;
    
    for (n in set)
      result++;
      
    return result;
    
  },
  
  any: function(set) {
    
    var n;
    
    for (n in set)
      return true;
    
    return false;
    
  },
  
  intersection: function(a, b) {
    
    var result = {};
    var k;
    
    for (k in a) {
      if (b[k])
        result[k] = true;
    }
    
    return result;
    
  }
  
};
